The present application relates generally to classifiers for use in the separation of particles of a substance according to size, density, or mass. More specifically, the present application relates to classifiers configured to more accurately separate the solid particles of a substance, such as a fuel (e.g., coal) to make the combustion of the fuel in a downstream process or device more efficient and to reduce undesirable emissions, or for other substances used in other industries, such as the solid particles used to form cement.